1. Field of the Invention
The present invention generally relates to methods and systems for estimating, monitoring and managing road traffic. More specifically, the present invention proposes a method and a system for precisely forecasting transit times or average transit speeds on roads of a monitored roads network.
2. Description of the Related Art
The estimation, monitoring and management of road traffic are nowadays normally accomplished based on information provided by sensors and video cameras deployed along the roads of the roads network to be monitored, and/or by police officers on the field, and/or by indications provided by phone directly by the vehicles' drivers driving on the roads network.
Methods and systems are also known exploiting information provided by vehicles (called “floating cars”) equipped with GPS receivers, which are capable of determining and communicating the geographic location of the vehicles.
In recent years, cellular mobile telephony networks (cellular PLMNs—Public Land Mobile Networks) have also been used for the purposes of estimation, monitoring and management of the road traffic, thanks to the widespread presence of mobile phones among the population. An advantage of these methods is that they do not require the deployment of additional infrastructures (like sensors, video cameras, GPS receivers) and allow capillary estimation of the roads' traffic conditions.
For example, in U.S. Pat. No. 6,577,946 location information obtained and continuously updated from vehicular-based cellular phones is collected, processed and used as a basis for input to intelligent transportation systems, in particular to real time urban traffic guidance for vehicular congestion and intelligent traffic control systems. Location information is obtainable from wireless location systems such as GSM in Europe, CDMA in the USA, or PDC in Japan, and depends on supporting technologies, which are in the process of perpetual improvement. Relying on cellular networks location system capabilities to provide moderately reliable position information, the records of vehicle phones coordinates, timing, etc., are collected, updated and stored in the traffic service center database. Those records together with digital maps are fed into mathematical models and algorithms that construct lists of vehicles traveling on various road sections, traffic loads at particular road sections, real time travel times along all road sections resulting from traffic congestion in particular areas, turning loads for signal intersections, and other key parameters necessary for real time functioning of intelligent transportation systems, in particular of intelligent traffic control systems, route guidance systems, etc.
In U.S. Pat. No. 6,650,948 a method is described for monitoring vehicular traffic flow in a road network in an area served by a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positioning system providing positional data for active mobile telecommunications devices. The method comprises capturing geographical positioning data for individual active devices carried aboard vehicles and converting these into probability vectors representing the likelihood of the vehicle having arrived at any of the possible road components of the road network compatible with the geographical positional data. As the vehicle travels along, this process is repeated and new probability vectors constructed based on the probability of any of the available routes between the new probability vector road component position and the immediately preceding probability vector road component position. The expected transit times for the available routes are computed and compared with actual transit times to provide delay factors for the available routes and thereby the road components thereof. Average delay factors are obtained by making use of data obtained for other vehicles thereby to provide a report indicative of the degree of traffic congestion and delay on the roads.
WO 07/077,472 discloses a road traffic monitoring system comprising: a first input for receiving position estimations of mobile terminals; a second input for receiving input specifications chosen depending on the type of service for which such monitoring is performed; and an output for generating road traffic maps, each road traffic map being associated with a set of territory elements and including, for each one of the territory elements, at least one mobility index of mobile terminals travelling within such territory element. Preferably, input specifications are chosen among at least two of the following parameters: territory element, territory element observation time slot, maximum allowable error on the estimation of said at least one mobility index.
In EP 763807 an estimation of traffic conditions on roads located in the radio coverage areas of a wireless communications network based on an analysis of real-time and past wireless traffic data carried on the wireless communications network. Data analyzed may include, for example, actual (current) and expected (past average) number of a) active-busy wireless end-user devices in one or more cells at a particular period of time, b) active-idle wireless end-user devices registered in a location area of the wireless communications network, c) amount of time spent by mobile end-user devices in one or more cells at a particular period of time.
U.S. Pat. No. 5,465,289 discloses a method and apparatus for providing vehicular traffic information using presently existing cellular telephone system technology. Traffic sensors monitor the control and voice channel transmissions of cellular units within a cellular telephone system. Data from these transmissions is extracted and analyzed according to a statistical model and derived vehicle geolocating information to generate vehicular traffic information that is transmitted to a central control center. By combining the information from all of the traffic sensors and each individual cell within a cellular telephone system, a picture of the traffic conditions existing along major thoroughfares may be determined.